Reduced-order modeling techniques are now commonly used to efficiently simulate circuits combined with interconnect, but generating reduced-order models from realistic three-dimensional (3-D) structures has received less attention. In this paper, we describe a Krylov-subspace based method for deriving reduced-order models directly from the 3-D magneto-quasistatic analysis program FastHenry. This new approach is no more expensive than computing an impedance matrix at a single frequency